Rolls Royce has won a $5bn (£3.2bn) contract from Delta Air Lines to deliver engines for 50 aircraft.
The company will also provide care and support services to the aircraft, which will include 25 Airbus A350s and 25 A330neo aircraft.
Rolls Royce has had a relationship with Delta Air Lines for over 40 years and Delta already uses Rolls Royce engine to power 55 aircraft.
Nat Pieper, vice president of fleet strategy and transactions at Delta, said:
We are pleased to be working closely with Rolls-Royce to power aircraft that will be a vital part of our future, providing a new level of excellence on our Pacific, Atlantic and Latin American routes.
John Rishton, chief executive, Rolls-Royce, said:
We are proud to be selected to power Delta's new generation of aircraft and look forward to deepening our relationship with a long-standing and valued customer.It is further evidence of the success of the Trent XWB in the market and represents a powerful vote of confidence in our newly-launched Trent 7000.
Investors will be keenly watching Rolls Royce's share price after today's announcement.